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A fault-tolerant observer design methodology is proposed. The aim is to guarantee a minimum level of closed-loop performance under all possible sensor fault combinations while optimizing performance under the nominal, fault-free condition. A novel approach is proposed to tackle the combinatorial nature of the problem, which is computationally intractable even for a moderate number of sensors, by recasting the problem as a robust performance problem, where the uncertainty set is composed of all combinations of a set of binary variables. A procedure based on an elimination lemma and an extension of a semidefinite relaxation procedure for binary variables is then used to derive sufficient conditions (necessary and sufficient in the case of one binary variable) for the solution of the problem which significantly reduces the number of matrix inequalities needed to solve the problem. The procedure is illustrated by considering a fault-tolerant observer switching scheme in which the observer outputs track the actual sensor fault condition. A numerical example from an electric power application is presented to illustrate the effectiveness of the design. [ABSTRACT FROM PUBLISHER]

In this technical note a decentralized controller-observer scheme for a multi-agent system is presented. The key idea is to develop, for each agent, an observer of the collective system's state and a motion controller. The observer is updated using only information from the agent itself and from its neighbors; the motion controller is designed in order to allow the team's weighted centroid to track an assigned time-varying reference. Convergence of the overall scheme is proven for directed and undirected communication graphs; moreover the extensions to the case of switching communication topologies and to the presence of saturation in the control input are discussed. Finally, numerical simulations are illustrated to validate the approach. [ABSTRACT FROM AUTHOR]

In this paper, we present a new sensor fault tolerant control scheme for linear, discrete-time systems. The scheme consists of a bank of estimators, each associated with a sensor or group of sensors, a mechanism for the detection and identification of sensor transitions from healthy-to-faulty and faulty-to-healthy operation, an estimate reconfiguration module, and an estimate-based feedback controller with reference tracking. The detection and identification approach is based on the separation of “healthy” and “faulty” sets, where appropriately selected residual variables remain under healthy or faulty operation, from “after-fault” and “after-recovery” sets, towards which the residual variables “jump” when abrupt sensor faults or recoveries occur in one or more groups of sensors. This “set-separation” approach provides pre-checkable fault tolerance guarantees whenever certain conditions, given in terms of system's known data such as plant and estimator dynamics and bounds on reference and disturbance signals, are satisfied. [ABSTRACT FROM PUBLISHER]